How do you turn a bunch of bones into a gorgeous picture of a Gorgosaurus? In a newly published book, two paleontologists and an artist from Australia describe the process that's worked for them for more than 30 years.

The Monash Science Center's Patricia Vickers-Rich and her husband, Museum Victoria's Thomas Rich, write about the paleontological groundwork that they do to figure out how extinct species looked — and how they lived. Freelance artist Peter Trusler, who was trained in zoology at Monash University, writes about how he builds on that groundwork to flesh out his pictures of those species. But it's clear that their method is not just a one-way assembly line leading from the fossils to the finished product.

"Sometimes the horse leads the cart, and sometimes the cart leads the horse," Trusler told me.

The way Trusler sees it, his illustrations are often "another one of the investigative tools in science to try to increase our understanding." And the Riches appreciate what he does.

"Peter is not only an artist," Thomas Rich told me. "He's also a very well-qualified scientist. He could have easily gone down that academic route, so you're not talking about a person who just draws pretty pictures."

Patricia Vickers-Rich agreed: "He's basically a scientist, too. He just happens to be a scientist who has a good style of art. ... We've got a very special guy there."

Trusler, who will be going for his Ph.D. under Vickers-Rich's guidance, goes out on expeditions just like the other scientists. "In some cases, I've sent Peter in the field in place of me," Vickers-Rich said. "If there was not a lot of money, I would send him."

Tom Rich recalled the time Trusler went out and gathered up some ginkgo leaves, then cut incisions into the leaves to get an idea of what the ancient Ginkgoides australis species looked like. Trusler often asks questions about how a particular anatomical feature might have worked, or how a creature's surroundings might have looked in ancient times. "If we couldn't provide the answers, he would go out and find a way to supply the answers," Rich said.

It's not cheap to document the discoveries made by paleontologists, Vickers-Rich pointed out. Supporting the effort requires major-league fundraising.

"It doesn't just come in your back door and somebody says, 'Here's $100,000, now go for it,'" she said. "Therefore, if you're going to do something like that, you need to be as accurate as you possibly can. From the point of view of a scientist, why would want a generic background? If you're going to put something out there that's unique, you don't want to just paint a green tree. You've got to know what kind of leaves to put on it. You have to know how tall it might have grown. You have to know the soil type. You have to know the geochemistry ... you need to know all that. I think what makes this art somewhat different from a great number of art pieces out there is, that care has been taken. If you're going to do generic, you just don't do what I do."

The better-than-generic results of the team's labors are on full display in the book — fossils gathered during the Riches' travels in Australia, New Zealand, Asia, the Americas, Africa and eastern Europe, plus sketches and paintings by Trusler that end up providing a photorealistic view of the past. The artist as well as the scientists are based in Australia, so much of their story is set Down Under. But their work has become known worldwide.

The weirdest pictures come not from the age of the dinosaurs, but from earlier or later — from the Precambrian, for example, a time when body plans apparently took on strange shapes that are hardly ever seen today. Or from the time when giant birds and mammals ruled the roost in Australia, just before the humans arrived.

You won't find feathered dinosaurs amid the pages of "The Artist and the Scientists," but stay tuned. Thomas Rich says he's focusing in on sites in Australia that are similar to China's Liaoning deposits, where the best evidence of dinosaur feathers has been found. Right now he has his eye on fossil beds near Koonwarra. "That's where we should go and look really hard for feathered dinosaurs," he said.

Meanwhile, Trusler is trying to figure out how to render a particular species of ichthyosaur, the ancient marine reptiles that ruled the seas while the dinosaurs held sway on land. "I don't have an idea in my head about what the final appearance of this animal is going to be," he said. "Your creativity is at play to a certain degree all the time, but the ultimate product is quite a mystery."

Thankfully, it's a mystery Trusler doesn't have to tackle alone. That's the main message of "The Artist and the Scientists."

"It's not simply a step-by-step process, in terms of me translating something that's set in concrete," Trusler said. "The process is quite an interactive one, and it always will be."

Be sure to click through "Bringing Prehistory to Life," a slideshow featuring photos and illustrations from "The Artist and the Scientists," published by Cambridge University Press.